Flue-expander.



P. CLARK.

PLUE EXPANDER. APPLICATION nun no. 9, 1907.

Patented Dec. 8, 1908.

2 SHEETS-SHEET'Z.

u I I I u 0 UNITED STATES FREDERICK CLARK, OF MINNEAPOLIS, MINNESOTA.

FLUE-EXPANDER.

To all whom it may concern:

Be it known that I, FREDERICK CLARK, a citizen of the United States, residing at Minneapolis, in the county of Hennepin and State of Minnesota, have invented a new and useful Flue-Expander, of which the following is a specification.

My invention has for its ob'ect to provide an extremely simple and highly eflicient flue expander, and to this end, it consists of the novel devices and combinations of devices hereinafter described and defined in the claim.

The invention in the preferred form is illustrated in the accompanying drawings, wherein like characters indicate like parts throughout the several views.

Referring to the drawings; Figure 1 is a view in side elevation showing the complete flue expander. Fig. 2 is a side elevation showing the spindle removed from workin position. Fig. 3 is a vertical longitudina section taken on the irregular line 90 m of Fig. 4, and showing the flue expander in operat've position; and Fig. 4 is a transverse vertical section taken on the line a as of Fig. 3 looking in the direction of the arrow.

My improved flue expander is made up of two main elements and a multiplicity of rollers. One of the main elements is in the form of a sleeve with radial slots to receive and space the rollers, and the other main element is in the form of a s indle that has threaded engagement with t e roller retaining or spacing sleeve and isrigidly secured to and preferably integrally formed with a taper-roller engaging mandrel. Three rollers are preferably employed so that the entire expander, in its preferred form, is made up of but five pieces.

Specifically described, this improved expander comprises as follows: The roller re taining and spacing sleeve 1 near its inner end is formed with three radial seats 2 which, at the perimeter of the sleeve are slightl less in width than the diameter of the cylindrical rollers 3, so that the said rollers will not drop outward through the said seats. Just outward of the radial seats 2, the sleeve 1 is formed with a radial gage flange 4 that is adapted to engage with the outer end of a flue 5, or with a flue sheet 6, to limit the movement of the rollers into the said flue, and thus properly position the rollers for action on the flue.

The spindle 7, at its intermediate portion,

Specification of Letters Patent.

Application filed December 9, 1907.

Patented Dec. 8, 1908.

Serial No. 405,833.

is externally threaded for engagement with internal threads 8 of the sleeve 1, and it is formed integral with a tapered expanded mandrel 9 that tapers in a direction from the i outer toward the inner end of the said spindle or from the outer end toward the screwthreaded-portion of the spindle. The large end of the said tapered mandrel 9 is of less diameter than that of the internal threads 8 of the sleeve 1, so that, in assembling of parts, the said mandrel may be passed freely through the internally threaded bore of the said sleeve 1.; At its outer end, the spindle 7 is formed with an angular head 10 to which a wrench or similar tool may be applied for the purpose of rotating the said spindle and mandrel. Also, as shown, the said head 10 is provided with a transverse perforation 11 through which a rod may be passed for the purpose of rotating the said spindle and mandrel.

The mandrel 9 is tapered in a direction from the outer toward the inner end of the spindle, so that the cylindrical rollers will give the greatest expansion to the flue at the inner edge of the flue sheet.

The operation of the improved flue expander described is as -follows: hen the rollers are to be inserted into the end of a flue, the spindle 7 is screwed into the sleeve 1 so that the smaller portion of the tapered mandrel 9 will engage therollers and permit sufflcient contraction of the several rollers to permit of the easy insertion thereof into the flue; and, when the expander has thus been properly positioned, the spindle 7 is again screwed outward until the tapered mandrel has forced the rollers outward into contact with the inner surface of the end of the flue. Then, by the wrench or other tool applied to the head of the spindle, the said spindle and mandrel are positively rotated in a direction which will tend to screw the said spindle outward in the sleeve 1. This gradual outward movement of the tapered mandrel, while it is being rotated, will gradually force the rollers outward, and thus gradually dilate or expand the engaged end of the flue. The rollers will have tight engagement both with the tapered mandrel and with the inner surface of the flue, and there will be a true rolling action between the said tapered mandrel and the flue. Under this rolling action, the rollers will travel in the same direction in which the mandrel is rotated, and they will cause the sleeve 1 to rotate in the same direction in which the said spindle and mandrel are retated, but, as the engaging points between the said rollers and the seats 2 of said sleeve are slightly outward of a circle intersecting the axes of said rollers, the advance rotary movement imparted to the said sleeve 1 will be slightly less than one-half of that of the said sleeve and mandrel, and, as is evident, this differential rotary movement between the spindle and mandrel will gradually draw the former and the mandrel outward. into said sleeve and thus cause the rollers to gradually expand the flue. There is, however, a very considerable friction between the threads of the spindle and of the sleeve, and, in practice, I have found that when the rollers are forced outward too rapidly, this friction between the threads of said spindle and said sleeve will become so great as to temporarily lock the sleeve to said spindle, and thus, for a time, lock the two for common rotation, thereby discontinuing the outward movement of the rollers until the flue has been expanded sufficiently to relieve, to some extent, the pressure between the rollers and flue. Otherwise stated, up to a certain point the rolling frictional contact between the rollers and the mandrel and flue will overcome the sliding frictional contact between the threads of the spindle and sleeve, and thus control the speed of rotation of the said sleeve; but, under excessive pressure produced by too rapid outward feeding of the rollers against the flue, the sliding frictional contact between the threads of the spindle and the sleeve will become the controlling factor and will temporarily cause the said spindle and sleeve to rotate together. It is, of course, obvious that when the spindle and sleeve rotate together, there will be no differential of movement between the said spindle and sleeve, and consequently, no outward movement of the tapered mandrel in respect 1 to the sleeve and rollers. This action is very important in the practical operation of the flue expander, and makes the expander perfectly automatic in its outward feeding of the rollers. Other highly important actions result from this outward tapering of the mandrel, to-wit, in addition to the above noted function of giving the greatest expansion to the flue at the inner edge of the flue sheet, it produces an outward taper in the end of the flue which prevents the rollers from being drawn outward by the outward movement of the tapered mandrel, and, furthermore, causes the mandrel and the sleeve to reversely draw upon or react against the said rollers, which latter feature, in itself, eliminates all tendency to move the rollers endwise on the flue. It is also highly important to note that it is the tapered mandrel and not the sleeve that performs the function of imparting traveling motion to the rollers, and performs this function not by a pushing action but purely by a rolling contact therewith, which results also in a pure rolling contact between the rollers and the flue.

- What I claim is:

In a flue expander, the combination with an internally threaded sleeve and a plurality of rollers carried thereby and movable radially therein, of a threaded rod with a mandrel tapered toward the threads thereof and with the large outer end of said mandrel of less diameter than the diameter of the threads, whereby the said tapered mandrel may be inserted through the internally threaded sleeve in advance of the threads of said rod, which mandrel operates on said rollers to force the same outward, substantially as described.

FREDERICK CLARK. Witnesses C. B. Snow, ALVOR-D C. EGELSTON. 

